Apparatus for curling thermoplastic threads



Aug- 23, 1960 H. A. SCHRENK ETAL 2,949,723

APPARATUS FOR CURLING THERMOPLASTIC THREADS Filed March 13. 1958 7 47 i\IIW v0.1 49 M W 9 A. 1

INVENTORS v HANS ALWIN SCHRENK PIETER VAN DIJK JAMES WATT IJSBRANDHEIJNIS BY i ATTORNEY 2,949,723 Patented Aug. 23,- 1960 APPARATUS FGRCUREENG THERMOPLASTIC THREADS Hans Alwin Schrenk, Arnhem, Pieter vanDijk, Velp,

and .lames Watt ljsbrand Heijnis, Arnhem, Netherlands, assignors toAmerican Enlra Corporation, Erika, Nil a corporation of Delaware FiledMar. 13, 1958, Ser. No. 721,281 Claims priority, application NetherlandsMar. 18, 1957 Claims. (Cl. 57-34) This application is acontinuation-in-part of application Serial No. 657,844, filed May 8,1957, now Patent No. 2,855,750. in that application, a false twistingapparatus including a high speed spindle is described for use incombination with a source of thread supply, a twist stop, a threadheater, a cooling zone, and a thread discharge device in the curling ofthermoplastic threads. The false-twisting spindle more particularlycomprises a rotatably mounted tubular spindle which is pressed by meansof a driving belt into two or more throats, each formed by a number ofdiscs which are freely rotatable around different shafts, at least oneof the disc rims cooperating with a peripheral groove in the spindle. Asdescribed in column 6- of the above-identified patent, it is preferredthat only two pair of discs, each pair form ing one throat, be utilizedfor supporting the false-twisting spindle. The shafts of the discs aremounted on a base plate which is transversely movable with respect tothe driving belt. A locking mechanism is provided which in the operativeposition of the spindle does not touch the latter but in the withdrawnposition of the base plate keeps the spindle with its peripheral groovein contact with a disc rim.

With the apparatus described, it is possible to curl thermoplasticthreads operating at a velocity of up to 60 m./min., since thefalse-twisting device may be rotated as fast as 180,600 revolutions perminute.

in operation, it has been found that certain problems are involved inapplying a sufficient amount of heat to a thread running at theserelatively high velocities to fix the twist imparted by the false twistdevice.

it is an object of this invention to provide an improved apparatus forcurling thermoplastic threads.

Another object is to provide such an apparatus having an improved threadheater device associated therewith.

Still another object is to provide an apparatus for curlingthermoplastic threads which has improved operational features.

A further object of the present invention is to provide a unitary heaterand false-twisting spindle assembly which may easily and quickly beshifted and held either in operative or inoperative position of thespindle.

Other objects will be apparent from the following detailed descriptionwhen taken in conjunction with the accompanying drawing which shows inperspective one embodiment of the present invention.

In general, the apparatus of the present invention is characterized byhaving a tubular heating element with a maximum inner diameter of 0.8mm. The tubular heating element is connected to a pivotally mounted baseplate coaxial with the false twist spindle. Improved means are alsoprovided for bringing the false twist spindle into driving relation withthe driving belt.

Upon mounting the tubular heating member on the base plate in theindicated position, it was found that during normal use of the devicethe thread obtains a vibrating movement between the thread guide mountedin front of the heating device and the false-twisting device. In thisway, a maximum heat transfer is obtained from the wall of the smallheating tube to the thread. This makes it possible to achieve a thoroughheating of the twisted thread with small heating tubes of a relativelyshort length. Such intensive heating is essential for obtaining a threadwith optimum curling properties.

The mounting of the small heating tube on the base plate makes itnecessary to connect the small tube to a source of energy in a movablemanner. In order to keep this connection as simple as possible, it ispreferred in those cases where the heating device is mounted above thefalse-twisting device to suspend the base plate swingably and to hold itin the operative position with the aid of a hook. This hook may serve topress the false-twisting spindle more forcibly or less forcibly againstthe belt driving system, as desired.

in this embodiment of the invention, the hook may operate in connectionwith an arm one end of which is rotatable around a shaft fixed parallelto the axis of swinging of the base plate on the frame of the machine.The hook portion comprises a tensioning pin extending from said arm in adirection parallel to the axis of rotation thereof, the tensioning pinbeing adapted to move over a running-on cam provided on the base plate.Moveent of this pin over the cam serves to urge the movable base platetoward the driving belt.

To prevent the swingably mounted base plate from moving out of thenon-operative position to the operative position under the influence ofgravity as a result of which the false-twisting spindle would start torotate at an undesired time, a spring may be provided which tends toresist the swinging movement of the base plate into the operativeposition.

It may be desired to cool the thread with the aid of a small coolingtube having an inner diameter of not more than 0.8 mm. after heating butbefore passing through the false-twisting device. If so, the coolingtube may preferably also be fixed to the base plate and disposedcoaxially with respect to the false-twisting spindle in its operativeposition.

The invention will be further elucidated by reference to theaccompanying drawing showing in perspective an embodiment of the deviceaccording to the invention.

In the drawing reference numeral 10 denotes generally a false-twistingdevice comprising a tubular spindle 11 provided with an elongatedperipheral groove 12, represented here as a reduced diameter portion,extending longitudinally of the spindle from immediately above theuppermost supporting disc to immediately below the lowermost disc. Fordetails on the dual operation of this groove as a running or supportingsurface and also as a means for preventing axial displacement duringoperation of the spindle, see the aforesaid US. Patent No. 2,855,750.

On the under side of the tubular spindle 11 3. diametrically extendingbracket 13 has been formed in the under side of which a perforatedsapphire thread guide 14 has been clamped.

Driving belt 15 exercises a pressure against the spindle 11 when thefalse-twisting device is in the operative position. This driving belt,of which only a portion is shown, is actuated by any suitable drivingmechanism (not shown). The belt 15 is pressed against the spindle 11 bymeans of guiding rollers 16 of which only one is shown in the drawing.The pressure exercised by the driving belt 15 keeps the spindle 11 atthe upper rim and at the lower rim of the groove 12 in contact with therims 17 of a couple of discs 18, these n'ms consisting of a wearresistant rubber. Discs 18 are fixedly arranged with two others in pairson, shafts 19 which. are rotatably.

3 mounted balltrear-iri-gs The dism 18 of each pair are arranged at sucha distance from each other that in the operative position of the spindle11 all discs are in contact with the peripheral groove 12 therein.

The roller bearings 20 are fixed in a base plate generally indicated 22.Said base plate 22' consists" oftwo parts, a horizontal part 34 and avertical: part 35. A column 23 is connected to" the horizontal part 34of the base plate 22. A'pair ofhooks 24 are fixed to the'column 23.These hooks do not touch the spindle 11 when it is in the operativeposition. However, on bringing the false-twisting device out of theoperative position, at which time the belt pressure is removed, hooks 24catch the spindle 11 before the elastic rims 17 come out of theperipheral groove on the spindle. Anopening 25 is provided in'the part34 of the base plate to permit passage th'erethrough of the threadbeingprocessed.

The vertical part of the base plate 22 is providedwith a pair oftenons-36 which test in jaws 37 formed in the free ends of arms 38. The arms 38are fixed to the frame (not shown) of the machine by means of asupporting rod 39. This makes it possible to pivot the unitary assemblycomprising the base plate 22- and the vertical part 35 around thehorizontal axis defined by tenons 36. When this movement occurs, spindle11 is moved toward or away from driving engagement with belt 15. y

A running-on cam 26 is attached to the plate 35 by any suitable meansanda limiting pin 27 extends from said cam 26. A tensioning: pin 28,adaptedto cooperate with the can 25, extends sideways from a tensioninghook 29. The hook-29, whichis at one end provided with a jaw 38, is atthe other end rotatable around a shaft 31 connected to the frame of themachine.

The shaft 31 is further provided with a block-shaped support32 to whicha spring 33 is connected. The length of the spring 33 is such that whentensioning book 29 is in the position shown in the drawing the spring istensioned. W p

Onthe vertical part 35 of the base plate a strip 41 of insulatingmaterial, such as asbestos board, is fixed. In

the upper end of this strip there is a bore 42 in which a.

small block 4.3 is arranged inn-freely shiftable position. Between thebottom of the bore 42 and the block 43 a sprin 44 is provided, whichspring iritbe position shown is somewhatcompresscd andthe'reforeeirercises an upwardly directed force on the small block 43 Across-arm 45 extends from the small block 4-3, the arm consisting of amaterial which may conduct electric due rent. A second cross-arm 46consisting of a similar material extends from the lower side of thestrip 41 of ihsulating material.

The cross-arms 45 and 46 are connected to a small metal tube 47foi'ine'd from resistance material and with an inner diame'tei" of 0.6aiida wall thickness of 0.2

- mm. current reed wires 48 and 49 are linked up with the arms 45 and46. p

By the "ction' off the: spring 44 the small tube 47 is kept in astretched condition. The sman tube 47 is surrounded by a mantle 50 toprevent as much cooling of the small tube aspes'sibte. Mantle 50 may beconstructed of any suitable material such phenol-formaldehyde typeplastic. A thread guide 51 is mounted above the entrance of the smalltube 47 for guiding a thread before entering the small tube. A secondthread guide 52 hired to the column 23 serves to guide thethread afterleaving the false-twisting devise. Both thread guides 51 and 52 arecoaxially mounted with the small heating tube 47 and the spindle 11 whenthe latter is in operative position. In order to be able tofi use theabove-described device for curling thermoplastic threads '21 bobbinholder, a thread supplying device and a twist stop (not shown) should bemounted abc'ive the thread guide 51- iri a known manner. Below thethread guide 52 there should further be provideda thread dischargedevice. In said cu'rlir'ig device the thread supplying device and thetwist stop may, if desired, comprise a pair of clamping rollersconnected with a driving mechanism. By such a combination the twistformed by the false-twisting device is prevented from running backfarther than to the clamping point of the rollers. A positively drivenroller may be used as the thread discharge device.

To operate the device a bobbin with the thread to be curled is placed onthe bobbin holder and the beginning of the thread is guided between theclamping rollers through the thread guide 51, the small heating tube 47,and the opening 25 to the false-twisting device 10. The thread is pulledfirst through the central bore of the spindle 11 and then with onewinding around the lower part of the mantle of the sapphire 14. Thethread is then passed through the thread guide 52 and via the threaddischarge device to a winding device. As soon as the small heating tubehas reached the required temperature and the apparatus is brought intomotion, the curling process starts.

For curling a 30 denier thread of polycaprolactam-having 10 filaments ata speed of 40 m./min., the belt 15 is driven at a velocity of 38m./se'c. Consequently the falsetwisting spindle 11 having a diameter of4.5 mm. is

' rotated at 160,000 r.p.m.- A preferred diameter of the discs is 40 mm.A heating tube having a length of 35 cm. at a temperature of to C. isused, an air path of 25 cm. being maintained between said tube and thefalse-twisting device. heating tube is not more than about 0.8 mm.

For deactivating the false-twisting device 10, for instance in case ofthread rupture, the tensioning book 29 is lifted so far that therunning-on cam 26 can move underneath the tensioning pin 28. As a resultof this the spring 33 may move the base plate 22 forward so that thespindle 11 comes free from the driving belt 15 and comes to a stop. Thespring 33 is so dimensioned that it is released before the tensioningpin 28 comes free from the cam 26. In this manner shifting of base plate22 into an inoperative position is facilitated,

In order to prevent the untimely swinging-through of the base plate inthe direction of the driving belt 15 the limiting pin 27 may be broughtinto the jaw 30 of the tensioning book 29.

The tensioning hook 29 is lifted in order to bring the spindle 11 intocontact with the belt 15. Due to this, the running-on cam 26 may passunderneath the tensionirig pin 28 after which the base plate 22 mayswing in the direction of the driving belt 15 until this movement isstopped by the spring 33. When lowering the tensioning hook 29 thetensioning pin 28 contacts the running-on cam 26 and presses the same onfurther movement downward of the tensionifig hook together with the baseplate 22 and the spindle 11 in the direction of the belt 15. Thismovement of the tensioning book 29 is limited by the limiting pin 27.

In order to prevent an upward movement of the tensioning book 29 duringthe curling operation, the lower part of the running-on cam 26 has acurve the center of which is coaxial with shaft 31. The curve of theupper part of the cam 26', however, is more pronounced than that of thelower part so that the loosening of the tensioning hook 29 over theupper part of the cam may be facilitated.

While moving the base plate 22 to and from the operative position, itwill be apparent that there is no change in the relative position of thesmall heating tube 47 and the false-twisting spindle 11. The correctposition of the small heating tube 47 relative to the false-twistingspindle is therefore always maintained. This position is fixed whenconstructing the machine for obtaining an optimum heating of the threadpassing therethrough.

Various modifications of this invention will be apparent to thoseworking in this field. It is therefore intended that the scope of theinvention will be measured by the following claims.

The inside diameter of the What is claimed is:

1. A device for curling thread comprising a tubular member adapted forrotation. and having at least two running surfaces from which the sameis supported, at least two pair of discs rotatable about spaced axes andhaving peripheral surfaces adapted to cooperate with said runningsurfaces to support said tubular member for rotation, drive means forimparting rotation to said tubular member, a tubular heating elementdisposed coaxially with respect to said tubular member in its operativeposition, a base plate mounting said supporting discs and said tubularheating element in spaced relationship, and means permitting pivotalmovement of said base plate toward and away from said driving means.

-2. A device for curling thread as set forth in claim 1 wherein thetubular heating element has an inner diameter of not more than about 0.8mm.

3. A device for curling thread as set forth in claim 2 wherein the baseplate is pivotally hung and is provided with cam means for guiding thesame into operative or inoperative position.

4. A device for curling thread as set forth in claim 3 provided with atensioning pin carried on a tensioning hook mounted for pivotal movementabout a shaft, said tensioning pin being adapted to move over thesurface of said cam means so as to guide said base plate toward or awayfrom said driving means.

5. A device for curling thread as set forth in claim 4 wherein springmeans are provided to resist the movement of said base plate intooperative position as said tensioning pin is moved over the surface ofsaid cam means.

References Cited in the file of this patent UNITED STATES PATENTS2,557,104 Hegediis June 19, 1951 2,791,086 Hilbert et a1. May 7, 19572,813,393 Kingsbm'y et a1. Nov. 19, 1957 2,829,487 Stoddard et a1 Apr.8, 1958 2,837,889 Comer June 10, 1958 FOREIGN PATENTS 276,601Switzerland Oct. 16, 1951 651,337 Great Britain Oct. 31, 1947 674,122Great Britain June 18, 1952

